Core drill



CORE DRILL Filed March 25, 1954 J, F. BOZEMAN' Feb. 23, 1937.

Jbhn F5 .Bozeman INVENTOR.

1 ATTORNEY.

Patented Feb. 23, 1937 UNITED STATES coma mum.

John F. Bozeman, Lake Charles, La., assignor tov Ace Wire Line Core Drilling Company, a corporation of Texas Application March 23,

6 Claims.

devices, such as that shown by the patent to 10 Barrett, et al, No. 1,847,424, have beenprovided whereby a core or sample of the formation may be obtained without the necessity -of removing the drill stem from the well, which consumes a -great deal of timeand is very expensive. In ap- 15 paratuses of this type, when a core or sample is desired, the core barrel is dropped into the drill stem and descends into an operative position, and after the core or sample has entered the barrel, the core barrel is removed upwardly through the drill stem by means of an overshot or fishing tool attached to the end of a cable,

whereupon drilling proceeds until another core, is

desired, when the operation is repeated.

It has also been found that as drills of the 25 type to which this invention specifically relates are adapted particularly for drilling soft formations,the boring tool of the core. barrel, which normally extends below the bit when 'the core barrel is in place, is so injured when a hard 30 stratum of formation is encountered that the core barrel cannot be withdrawn through the drill stem, and means have heretofore been provided to permit the boring tool to withdraw into the bit when hard formations are encountered to pro- 35 tect it from injury.

This invention has for its general object the provision of certain improvements in the apparatus covered by the said patent to Barrett, et al, No. 1,847,424.

A specific object of the invention is to provide a combination of parts, including a relatively large and strong spring which remains at all times inthe drill stem and exertsadownward pressure upon the core barrel, yielding upwardly 4 5 to permit the boring tool to withdraw into the bit when hard formations are encountered.

Another specific object is to provide a new and.

improvedinterengaging means between the core barrel and the drill stem which engage at a sub- 50 stantial distance from the longitudinal axis of the core barrel so that the strain thereupon is reduced and the parts are less liable to injury.

A further specific object is the provision of new and improved means to yieldably hold the 5 interengaging means in engagement and to eiiect 1934, Serial No. 116,990

' the positive release thereof upon an upward pull thereon.

Other objects will hereinafter appear.

The preferred embodiment of the invention is illustrated in the accompanying drawing, wherein Fig. 1 is a sectional elevation of the 'drill stem with the core barrel in place; Fig. 2, a view of the upper part of the ap aratus showing the parts in engagement; Fig. 3, a cross section on the line 3-3 of Fig. 2; and Fig. 4, a view showing the relative positions of the parts after they have been disengaged to permit withdrawal of the core barrel.

"In the drawing the drill stem is indicated at I, and the drill bit at 2. The latter may be of the conventional fish tail type, and has a central opening 4 of an internal diameter substantially greater than the external diameter of the core barrel 5. Vertically reciprocal in the drill stem 1 is a drive sleeve 6 held against rotation with respect to the drill stem by the key I fitting in the slot 8, and having a. spiral lower surface forming a depending abutment 6a. Above the sleeve 6 is a large and strong coil spring 9 to bear upwardly on the shoulder i formed by the drill stem coupling H, and downwardly upon said sleeve.

0n thelower end of the core barrel is a boring tool i2, and adjacent said end is a core catcher l3. At the upper end of the core barrel is a relief valve L4. The core catcher i3 operates in the usual manner to permit the core to enter the barrel 5 and to prevent it from falling out of the barrel 5 when the core barrel is elevated. The reliei valve 64 functions in the usual manner to permit the escape through the ducts 85 of fluid that would otherwise be trapped in the barrel 5 as the core rises therein, and to prevent the entranceinto the barrel 5 of the slush that is pumped through the drill stem. The core barrel 5 is connected by the coupling 56 to a cylinder H in which the releasing device 48 is reciprocable. The numeral l9 indicates a fixed pin by which thedog 20 is pivoted. The numeral N indicates a movable pin carried by the releasing device is and slidable upwardly in the slot '22 of the dog 20. Hooked on the pin 23 and engaging'the pin 24 in the releasing device i8 is a spring 25' to bear against the upper surface 26,- of the dog 20 when the parts are in the positionshown by Fig. 1 for reasons which will hereinafter appear.

The dog 2!! is movable through the slot 21 in the cylinder ll so that its portion 20a may engage underneath the ring 6 and against the abutment 6a. of said ring for the purpose hereinafter referred to.

The drill is used as follows:

During the drilling of soft formations the .drill is used without the core barrel in place, muddy water known as slush being pumped downwardly through the drill stem and out through the bore 4 in the bit 2 to keep the bit cool and to remove the cuttings thereof, the said slush rising upwardly in the well about the exterior of the drill stem to the surface of the earth.

-When a core or sample of the formation is desired, the drill stem I is elevated slightly to remove the bit 2 from the bottom of the well, whereupon the core barrel 5 is dropped into the drill stem. The core barrel 5 will descend until the enlarged portion 5b engages the shoulder 21. The drill stem is then lowered and rotated and the dog 20 will then become engaged under the ring 6 and against the abutment Go as shown by Fig. 1, the spring 25 serving to yieldablyhold the said parts insuch engagement. The drill stem thereupon rotates the core barrel 5 through the key I, sleeve 6 and dog 20 to drive the boring tool l2 below the bit 2 into the formation, slush being meanwhile pumped downwardly through the drill stem. To permit the passage of the slush downwardly between the drill stem l and the core barrel 5, the sleeve 6 may be provided with passageways 6b and openings 6c, and the bushing 28 is grooved as indicated at 29. The slush therefore passes through the bore 4 about the core barrel 5. As the boring tool l2 extends below the bit 2, the slush cannot enter the core barrel to contaminate the core.

Now, if a hard stratum of formation is encountered, the boring tool 12 may withdraw up into the bit 2 so that the weight placed upon the drill stem I is thereupon carried by the bit 2 and the bit 2 serves to protect the boring tool l2 from injury. Such withdrawal is permitted because the sleeve 6 is slidable upwardly in the drill stem I as the spring 9 yields. While the sleeve 6 may move upwardly, the rotation of the boring tool I2 is continued because the key I still remains in the groove 8. In other words, while the sleeve 6 may move upwardly in the drill stem i, it is at all times rotated by the drill stem l.

After the drill has passed through the hard stratum the spring 9 thereupon forces the sleeve S downwardly to extend the boring tool IE to its normal position below the bit 2.

After the core has entered the barrel b, the barrel may be removed by lowering into the drill stem E an overshot 2% on the end of a cable not shown. Overshot is will engage the head 3% of thereleasing device It, and when an upward pull is exerted on the cable, the releasing device 98 will be moved upwardly in the cylinder ll. Because of the angle between the surface 26 of the dog 29 and the adjacent wall of the slot 22, the tension'oi the spring 25 will be relieved so that the spring 25 will no longer urge the dog 28 outwardly. Pin 2%, carried by the releasing device it, will then continue to move upwardly in the slot 22 pulling the dog 26 inwardly out of engagement wlth the ring 6. The core barrel will then be free for upward movement through be mentioned: 1

The spring 9 is a strong, relatively, large, spring adapted to exert any desired, downward pressure on the boring tool l2, and to withstand severe strain. This size is made possible by leaving the spring 9 in the drill stem. If it were carried by the core barrel, it would necessarily have to be small to permit it to pass through the drill stem.

The key 1 is substantially remote from the longitudinal axis of the core barrel 5, so that the strain thereon is relatively small. This reduces friction between key I and the walls of the slot 8, andconsequently reduces wear.

In prior devices, yieldable means have been provided to urge outwardly into their active positions dogs corresponding to the dog 20, but it has been necessary to overcome the resistance of said means in order to move such dogs into barrel; a boring tool on the lower end of said core barrel; said drill stem having a shoulder therein; a sleeve vertically movable in said drill stem below said shoulder, and keyed against rotation in said drill stem and having a depending abutment; a spring in said drill stem between said sleeve and said shoulder; a dog pivotally carried by said core barrel and having an angular slot therein; a releasing device movable with respect to said dog and having a pin extending through said slot and yieldable means bearing against said dog to yieldably hold it in its active position; said core barrel being insertable downwardly in said drill stem and bit bore into an operative position and said dog being movable underneath said sleeve and against said abut ment when said barrel is in said position, and said boring tool being normally below said bit when said barrel is in said position; said spring serving to exert a downward pressure on said core 'barrel and to yield upwardly to permit said boring tool to withdraw up into said bit when hard formations are encountered; said core barrel being removable upwardly through said driil stem by an upward pull on said releasing device; said releasing device, pin and yieldable means being so associated with said dog that upon such upward movement the tension of said yieldable means is relieved and said pin moves said dog into its inactive position; said core barrel having a core catcher adjacent its lower end and a relief valve adjacent its upper end; and said elements being so constructed as to provide a fluid pas sageway to permit slush to be pumped downwardly through said drill stem and bit during coring operations.

2. In a rotary drill of the class described in the specification, the combination of a drill stern and a core barrel, of means between said drlll stem and core barrel to releasably hold said core barrel in said drill stem, said means including in 'terengaging elements carried by said core barrel and by said drill stem, yieldable means to urge said core barrel element into engagement with said drill stem element, and a releasing device to disengage said elements when an upward pull. is exerted on said device, said yieldable means'be ing operatively associated with said releasing device and being moved to' relieve its tension when an upward pull is exerted on said device.

3. A rotary-drill of the classdescribed in the specification, including a drill stem having a bit attached to the lower end thereof, a core barrel in said stem and having a-boring'g' tool attached to the lower end thereof and normally extending below said bit, and driving means between. said drill stem andco're barrel-said driving means including interengaging elements carried by said core barrel and drlllstem, said drill stem element having a helical lower sumeerog a depending abutment, and saidoore barrel element being arranged to slide on said surface into engagement with said abutment when said drill is rotated; I

d. In a rotary drill oi the class described, a drill stem having a bit atten-heel to its lower end and a core barrel insertable'" therein and removable therefrom ,andhaving a boring tool'to normally extend below the bit ng coring operations, means carried by said core-barrel adapted to engage a portion oiisaid drill stem to prevent upward movement of said core barrel with respect to said drill stem, resilient means for urging said first mentioned 1 r a into latching position'with respect to said drill stem, and means slidable withgrespeet to'said core barrel and adapted upon upward movement to first relieve the tension oiv said resilient ineans againstsaid first mentioned means and then to retract said mentioned means to unlatched position.

5. A rotary drill of the descri includanew ing a drill stem having a bit attached to the lower end thereof, a core barrel in said stem, and having a boring tool attached to the lower end thereof and normally extending below said bit. lnterengaging elements carried by said core barrel and drill stem, yieldable means to urge said core barrel element into engagement with said drill stem element, and a releasing device slidable with respect to said core barrel and forming a support for said yieldable means, said .ireleasin'g device being adapted upon upward movement with respect to said core barrel to first move said yieldable means away from said core barrel element and then to move said core barrel element out of engagement. with said drill stem element.

"6. In a rotary drill of the class described the combination of the drill stem and a core barrel, a latch on said core barrel adapted to engage said drill stem, a releasing device on said core barrel adapted to receive a tool forv removing 

